Method of fabricating a solder-on-pad structure and flip-chip bonding method using the same

1. A method of fabricating a solder-on-pad structure, comprising: providing a substrate with a pad; coating a solder bump maker including a first resin and a solder powder on the substrate; heating the solder bump maker to a temperature lower than a melting point of the solder powder, thereby aggregating the solder powder on the pad; removing the first resin, coating a second resin or a flux on the solder powder; reflowing the solder powder; and removing the second resin or the flux.

2. The method of claim 1 , wherein the solder powder comprises a ternary solder.

3. The method of claim 2 , wherein the ternary solder comprises SAC305 (Sn 3 Ag 0.5 Cu).

4. The method of claim 3 , wherein the SAC305 is heated to 215° C. during the heating of the solder bump maker.

5. The method of claim 1 , further comprising, forming a guide exposing the pad on the substrate and determining a height of the solder bump maker.

6. The method of claim 5 , wherein the coating of the solder bump maker is performed by a printing process, and the guide is used to print the solder bump maker on a specific region of the substrate, where the pad is provided, during the printing process.

7. The method of claim 1 , wherein the solder bump maker further comprises a reductant selected to remove a natural oxide layer from surfaces of the solder powder and the pad.

8. The method of claim 1 , wherein the reflowing of the solder powder is performed to heat the solder powder to a temperature higher than a melting point thereof.

9. A flip-chip bonding method, comprising: providing a substrate with a pad; coating a solder bump maker including a first resin and a solder powder on the substrate; heating the solder bump maker to a temperature lower than a melting point of the solder powder, thereby aggregating the solder powder on the pad; removing the first resin; coating a second resin or a flux; reflowing the aggregated solder powder to form a solder bump on the pad; and removing the second resin or the flux.

10. The method of claim 9 , wherein the solder powder comprises a ternary solder made of SAC305 (Sn 3 Ag 0.5 Cu).

11. The method of claim 10 , wherein the SAC305 is heated to 215° C. during the heating of the solder bump maker.

12. The method of claim 10 , wherein the solder powder is heated to a temperature higher than the melting point during the reflowing of the aggregated solder powder.

13. The method of claim 9 , wherein the substrate comprises a wafer provided with a trench.